TU‐G‐110‐01: Feasibility Study of Using Multi‐Pixel Photon Counter (MPPC) as Energy Resolved Photon Counting Detector

Purpose: Energy resolved x‐ray photon counting detector is an enable technique for energy resolved CT system. A popular choice is Cd‐Te or CZT direct conversion x‐ray detector. But this kind of detector suffers low counting rate and therefore is unsuitable in clinical imaging. Multi‐Pixel Photon Counter (MPPC) is a new device that potentially can achieve much higher photon counting rate. In this study, we investigated the feasibility of using MPPC as x‐ray photon counting detector. Method and Materials: We designed and assembled a MPPC photon counting module with a Hamamatsu MPPC coupled with a LYSO scintillator. The photon pulses were recorded by a GHz digital oscilloscope and stored in a computer. We developed a signal pulse model which can be used to determine the instance and height of each pulse. To further increase the counting rate, a signal processing algorithm was used to discern multiple partially overlapped pulses. Results: Based on the position and height of the MPPC pulses, the time and energy of an x‐ray photon event can obtain by fitting the model with measured signal. The developed signal processing algorithm can further differentiate x‐ray photons that are piled up together. A higher than 20 Mcounts/s can easily achieve by MPPC counters. Conclusion: MPPC photon counter coupled with LYSO scintillator can achieve a much faster photon counting rate than Cd‐Te or CZT detector. It is a promising x‐ray photon counter that potentially can reduce energy resolved CT scanning time to a clinically acceptable range.